The present invention relates to containers for storing and/or dispensing a substance, to closures for use with such containers, to parisons for use in blow moulding operations to produce such containers and closures and to methods of forming both the parisons and the containers either with or without an associated closure.
Plastic bottles and containers are generally formed of two separate components, a main body and a closure, the two components usually being manufactured by different process. The main body is usually manufactured by extrusion blow moulding, injection blow moulding or by injection stretch blow moulding. If the container is a straight sided container it is usually manufactured by injection moulding. By contrast, the closure is usually manufactured by injection moulding.
The two components are often manufactured in separate factories and are then transported to a filling production line where they are then separately sorted and orientated. The main body is placed on the filling line and filled with the required contents. The closure is then assembled onto the body. The assembled container is typically then labelled before a number of additional operations are carried out, such as adding a tamper evident feature in the form of a shrink wrap sleeve. It is to be noted however, that each of the components making up the container require separate sets of tooling, manufacturing infrastructure, inventory control and handling equipment.
As a manufacturing process, extrusion blow moulding offers the advantage that undercuts can be easily formed enabling the production of hollow containers having a restricted neck or the like. Although hollow shapes such as a handle can be formed within the volume of the container, this process has the disadvantage that solid integral homogeneous components, such as solid handles, cannot be formed concurrently with the container in the same operation. By contrast, injection blow moulding and injection stretch blow moulding offer methods of manufacturing hollow containers having a restricted neck and which also allow for the provision of integral solid components such as one or more handles. Unfortunately, injection blow moulding is more expensive to tool up for and therefore usually requires large production volumes to justify the higher tooling cost or else added value in the product produced. The product produced by injection blow moulding or injection stretch blow moulding is undoubtedly superior to that produced by extrusion blow moulding since greater control of wall thickness and tolerances is possible and no waste is produced. However, injection blow moulding has the disadvantage of limitations due to blow ratios. The maximum parison length to neck diameter ratio (L/D) is generally accepted to be 12 to 1.
Typically a security feature is provided for containers that require evidence of tampering. This is usually in the form of a separate component which needs additional manufacturing effort, separate tooling and inventory control and which must be assembled to the finished container, usually on the filling line.
A separate screw or push on closure or a separate dispensing orifice plug is provided for containers where a small orifice is required for the metering out of flowable contents. The orifice is usually smaller than the top opening of the main body such as is the case, for example, with plastic shampoo bottles.
A typical closure may be provided with a plain film hinge with which to attach a dispensing cap to the body of the closure. A spring feature may also be provided, either separate from the hinge and integral with the closure or else integral with the hinge, in order to generate a spring action to facilitate the positive opening and closing of the dispensing cap and to keep the cap in an open position when pouring.
It is also known to provide plastic containers having two openings. Such containers are typically in the form of dispensing tubes and are commonly used for the dispensing of tooth paste. The tubes comprise a top end having a restricted opening from which the contents of the tube are dispensed and a bottom end having an opening through which the tube is first filled but which is subsequently sealed. The tube type container has the disadvantage that it can not be stood upright on its sealed end as a single sealing edge does not provide a stable base.
Containers are typically labelled either by attaching a self adhesive, preprinted label to the main body or by screen or other printing methods. In tool labelling is also becoming more popular. Generally a moulded container will possess a raised split line as a consequence of the moulding process. The position of this split line on the container is critical if the container is to be screen printed.
In regard to the cycle time of slender plastic moulded parts, it is advantageous to gate the part close to the area of the greatest restriction, as the gate is the hottest part of the tool and this increases the filling time.
It is more important than ever for packaging design to maximise the efficient use of raw materials and minimise the overall energy consumption required to produce the finished container. It is therefore advantageous to combine several design features into a single embodiment to reduce cost, increase efficiency and to produce a more worthy product.
Containers are produced in many shapes and sizes and are manufactured from a wide variety of materials. They employ many closures types and several different processing methods are used.
Recycling of the plastic used in packaging is required by the public as a result of the attention now given to environmental issues. However, many plastic containers consist of two plastic types, one plastic type for the closure and one plastic type for the body. If the two types of plastic are recycled together the plastic re-grind quality is lower than it would be if the two components were separated. This however, is a time consuming task.